Cortex; a journal devoted to the study of the nervous system and behavior
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The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) and the behavioral variant frontotemporal dementia (bvFTD) are focal neurodegenerative disorders belonging to the FTD-spectrum clinical syndromes. NfvPPA is characterized by effortful speech and/or agrammatism and left frontal atrophy, while bvFTD is characterized by social-emotional dysfunction often accompanied by right-lateralized frontal damage. Despite their contrasting clinical presentations, both disorders show prominent left anterior insula atrophy. ⋯ ROI analysis of bilateral insula showed that the left SPGI was significantly more atrophied in nfvPPA compared to bvFTD, while the bilateral ventral anterior and right dorsal anterior insula sub-regions were more atrophied in bvFTD than nfvPPA. Only left SPGI volume correlated with speech production abilities, while left and right ventral anterior insula volumes correlated with ratings of aberrant eating behavior. These two FTD clinical variants show different patterns of insular sub-region atrophy in the left precentral dorsal anterior and bilateral ventral anterior regions, providing further evidence for the role of these sub-regions in speech production and social-emotional function.
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Discrete yet overlapping frontal-striatal circuits mediate broadly dissociable cognitive and behavioural processes. Using a recently developed multi-echo resting-state functional MRI (magnetic resonance imaging) sequence with greatly enhanced signal compared to noise ratios, we map frontal cortical functional projections to the striatum and striatal projections through the direct and indirect basal ganglia circuit. We demonstrate distinct limbic (ventromedial prefrontal regions, ventral striatum - VS, ventral tegmental area - VTA), motor (supplementary motor areas - SMAs, putamen, substantia nigra) and cognitive (lateral prefrontal and caudate) functional connectivity. ⋯ We further use neurite orientation dispersion and density imaging (NODDI) to show that more goal-directed model-based learning (MBc) is also associated with higher mOFC neurite density and habitual model-free learning (MFc) implicates neurite complexity in the putamen. This data highlights similarities between a computational account of MFc and conventional measures of habit learning. We highlight the intrinsic functional and structural architecture of parallel systems of behavioural control.
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Laughter is a complex motor behavior that, typically, expresses mirth. Despite its fundamental role in social life, knowledge about the neural basis of laughter is very limited and mostly based on a few electrical stimulation (ES) studies carried out in epileptic patients. In these studies laughter was elicited from temporal areas where it was accompanied by mirth and from frontal areas plus an anterior cingulate case where laughter without mirth was observed. ⋯ This large dataset allow us to offer a more reliable picture of the functional contribute of this region in laughter, and to precisely localize it in the cingulate cortex. We conclude that the pACC is involved in both the motor and the affective components of emotions, and challenge the validity of a sharp dichotomy between motor and emotional centers for laughing. Finally, we suggest a possible anatomical network for the production of positive emotional expressions.
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Observing the pain of others has been shown to elicit greater activation in sensory and emotional areas of the brain suggested to represent a neural marker of empathy. This modulation of brain responses to others' pain is dependent on the race of the observed person, such that observing own-race people in pain is associated with greater activity in the anterior cingulate and bilateral insula cortices compared to other-race people. Importantly, it is not known how this racial bias to pain in other-race individuals might change over time in new immigrants or might depend on the level and quality of contact with people of the other-race. ⋯ Crucially, activation in the anterior cingulate to pain in other races increased significantly with the level of contact participants reported with people of the other race. Importantly, this correlation did not depend on the closeness of contact or personal relationships, but simply on the overall level of experience with people of the other race in their every-day environment. Racial bias in neural responses to others' pain, as a neural marker of empathy, therefore changes with experience in new immigrants at least within 5 years of arrival in the new society and, crucially, depends on the level of contact with people of the other race in every-day life contexts.
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Randomized Controlled Trial
Delayed enhancement of multitasking performance: Effects of anodal transcranial direct current stimulation on the prefrontal cortex.
The dorsolateral prefrontal cortex (DLPFC) has been proposed to play an important role in neural processes that underlie multitasking performance. However, this claim is underexplored in terms of direct causal evidence. ⋯ These results suggest a causal role of left prefrontal cortex in facilitating the simultaneous performance of more than one task, or multitasking. Moreover, these findings reveal that anodal tDCS may have delayed benefits that reflect an enhanced rate of learning.